Not applicable.
Not Applicable.
This invention relates to a method of assembling a GEN III packaged bearing in a hub, and, in particular, to a method which facilitates the insertion of an outboard seal using an application tool.
The assembly of GEN III type packaged bearing products is difficult due to the minimal space between the outboard cup, housing, or knuckle face and the inboard face of the hub flange. A seal pressed into the bearing, housing or knuckle is required to minimize or eliminate contaminants entering the bearing from the roadway. Certain packaged bearing designs are such that the outboard seal cannot be installed prior to the installation of the rollers and cage into the bearing cup/housing or knuckle, therefore, the rollers and cage must be installed before the seal and the hub.
Two options are currently available to assemble this type of bearing. One is the design of a xe2x80x9cbelow centerxe2x80x9d cage in which the rollers are installed from the outside diameter of the cage, as opposed to the more traditional design in which rollers are installed from the inside diameter of the cage. xe2x80x9cBelow centerxe2x80x9d0 cage designs are not considered the standard method of retaining rollers in tapered roller bearings. Therefore, the cost of such items becomes higher than the more conventional cage design. Assembly of the bearing using a xe2x80x9cbelow centerxe2x80x9d cage design requires additional manipulation of the bearing cup, housing, or knuckle to install the rollers and cage, increasing the cost of the assembly.
Another option is to use a specially designed cage in which the rollers are contained in the cage. However, the use of a special cage design can result in increased cost and special assembly operations.
The problem to be solved is how to get the outboard seal of the hub unit in place. In a typical GEN II hub unit, the outboard seal is installed in the bearing before the bearing is installed on the hub. It is only when the outboard cone is integral with the hub, as in a GEN III hub unit, that it is difficult to install the outboard seal. The reason for this difficulty is that the outboard seal has to be in place on the hub before the rollers are installed on the hub and when the hub/seal/rollers are inserted into the cup, there must be some way to press the seal into the cup, housing, or knuckle with a tight fit.
GEN III ball bearings (as opposed to tapered roller bearings) have been in use for some time. However, since it is common for the balls of ball bearings to be held in the cage as a set, they do not encounter this problem, because the ball/cage set can be installed in the cup, and then the outboard seal pressed into the cup, housing or knuckle, and then the hub inserted into the cup.
There are a number of solutions when tapered rollers are used. A typical solution is to use a split puller that fits between the hub flange and the seal. This puller pulls the seal into place as the spindle is inserted into the cup. However, as the hub unit is made narrower, there is no room for the puller. This is especially true, if a ribbed flange (such as disclosed in co-pending application Ser. No. 981,539, filed Oct. 17, 2001, which is entitled xe2x80x9cWheel Hub With Stiffened Flangexe2x80x9d, and which is incorporated herein by reference) is used.
Other solutions involve the use of special cages or very large ID seals. For example, U.S. Pat. No. 6,287,015 discloses the use of a special cage in the outboard row that holds the rollers against the cup ID. Thus, the outboard rollers, cage, and outboard seal can be installed in the cup prior to assembly of the hub into the cup.
U.S. Pat. No. 6,135,643 discloses the use of a special cage in the outboard row that holds the rollers in the cage, much the same as is used for ball bearings. Again, the outboard rollers, cage, and outboard seal can be installed in the cup prior to insertion of the hub.
U.S. Pat. No. 5,037,214 discloses a special finger type cage. Here, the special cage is used to make a true GEN III bearing, wherein both cones are integral with the hub. The problem here is providing some way to get the rollers into the bearing. Getting the outboard seal in place is secondary, as there is sufficient clearance to pull it in with a puller.
U.S. Pat. Nos. 5,454,647 and 5,494,358 disclose less desirable solutionxe2x80x94namely that the outboard seal be big enough to pass over the rollers after the rollers and cage are assembled on the outboard integral cone.
Each of the noted solutions has its problems. Special cages cost more and require different roller loading equipment. Large diameter seals generate more heat. It would be preferable to develop a technique to assemble a hub assembly which uses a standard cage and which simplifies the placement of the seals in the hub assembly.
In accordance with the invention, generally stated, an application tool (and a method of use of the tool) is provided for assembling an outboard seal and roller assembly into a hub unit. The tool and method allow for the use of standard seals and cage/roller assemblies, thus avoiding the problem associated with the use of special cages or oversized large-diameter seals.
An application tool of the invention includes an outer member that is at least partially hollow and an inner member which is received within the outer member and is movable axially relative to the outer member. A biasing member (such as a spring element) is placed in the outer member to bias the inner member upwardly relative to the outer member. The inner member includes plurality of pockets formed about its outer surface and which extend downwardly from its upper surface. The number of pockets formed in the inner member outer surface correspond to the number of rollers to be inserted in the outboard row of the bearing assembly of the hub unit. The inner member also includes a bore extending axially downwardly from its member upper surface which is sized and shaped to receive a spindle of the hub. The outer member has an outer diameter sized to allow the application tool to slide adjacent to and axially relative to the hub outer raceways.
The method of assembling the outboard seal into a hub unit includes (1) providing a support member with at least an outboard outer race; (2) inserting the application tool into the outboard outer race; (3) placing a cage about the application tool with the small end ring of the cage resting on the upper surface of the tool outer member and with the cage pockets generally aligned with the application tool inner member pockets; (4) placing rollers into enclosures defined by the cage pockets and the inner member pockets; (5) ensuring that the rollers contact the outer raceway; (6) fitting an outboard seal into position on the support member; (7) inserting a hub into the support member to form a hub/support member assembly in which the outboard seal is engaged with a seal surface of the hub; and (8) separating the application tool and the hub/support member assembly from each other. When the cage and rollers are placed in the tool for insertion into the hub unit; the rollers may be axially spaced from the outboard outer raceway. Hence, step (4) above involves axially moving the tool relative to the support member (and raceways) until the rollers are in contact with the raceway. During step (7), the inner member is moved axially relative to the outer member.